Sour gas - A history of expertise - Total.com

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SOUR GAS
s
GTL and CO2
Produced CO2 can be
economically reclaimed in a
Gas-to-Liquids (GTL) conversion
reaction. This option is being
explored through research into
the Fischer-Tropsch GTL process,
which produces syngas then
converts it into liquid
hydrocarbons. The presence of
CO2 in the feedgas for the syngas
reactor improves the carbon
efficiency of the GTL conversion.
//. expertise
sUstAinAble
mAnAGement
of rEsiduAl products
s s s
Total is developing specific techniques to make
the development of sour resources as safe as possible
for the environment. Injection is an option that avoids
sulfur production and reduces emissions of CO2.
Sour gas processes generate emissions that have strong concentrations
of H2S — a lethal gas in even minimal doses — and that may also contain
CO2, entailing harmful effects on the environment. The safe and reliable
management of these so-called residual gases is a priority focus of
the Group’s Research & Development efforts.
solUtions for sUlfUr
H2S can be converted to sulfur using Total proprietary processes
in Claus units. In the first phase, part of the H2S is converted to SO2
in a thermal reaction: 2H2S + 3O2 ➝ 2SO2 + 2H2O. The SO2 is then
contacted with the remaining part of H2S for a Claus reaction yielding
sulfur: 2H2S + SO2 ➝ 3/2 S2 + 2H2O. With this option, sufficient energy
to power the gas sweetening units can generally be recovered provided
the H2S/CO2 ratio is high enough. The Group has also developed
Sulfreen, selective amine and other processes for treating residual
gases from sulfur plants, and possesses know-how in the area of
sulfur conditioning systems, notably for degassing liquid sulfur with
Aquisulf technology. In other words, Total can boast end-to-end
mastery of the chain: production, handling, storage, and sale.
The saturation of the sulfur market — a situation that is likely to last —
is prompting the need for new solutions for the storage of sulfur or
H2S. One option considered promising by many operators is injecting
residual acid gases directly into depleted reservoirs. This can be
facilitated by using the Sprex ® process, as it enables the separation
of H2S under high pressure. Implementing this solution requires
complete control of corrosion and all other aspects related to the
extreme toxicity of H2S. The risks and uncertainties involved in storing
H2S in geological reservoirs must also be fully mastered. This is one
of the major challenges facing the Group as it pursues research in
this extremely complex field.
Residual acid gases can also be used to enhance oil recovery (EOR),
but to avoid the risk of cycling these gases into the producing wells,
thorough knowledge of the reservoir and mastery of material-flow
modeling are imperative.
solUtions for Co2
Although the residual CO2 from treating sour gas is less hazardous than
the H2S, it nonetheless contributes to climate change. The Group’s
objective is thus to release as little of it as possible into the atmosphere.
Total is therefore studying options such as CO2 storage in depleted